Figure 1. GLP-1 (7-37)-induced concentration-dependent stimulation of intracellular calcium mobilization in CHO-K1/GLP1R/Gα15 cells. The cells were loaded with Calcium-4 prior to being stimulated with agonist GLP-1 (7-37). The intracellular calcium change was measured by FLIPR^TETRA. The relative fluorescent units (RFU) were normalized and plotted against the log of the cumulative doses (5-fold dilution) of GLP-1 (7-37) (Mean ± SEM, n = 3). The EC₅₀ of GLP-1 (7-37) on this cell was 0.14 µM.

Notes:
EC₅₀ value is calculated with four parameter logistic equation:
Y=Bottom + (Top-Bottom)/(1+10^((LogEC₅₀-X)*Hill Slope))
X is the logarithm of concentration. Y is the response
Y is % stimulation of RFU and starts at Bottom and goes to Top with a sigmoid shape.

Figure 2. FACS analysis of cell surface expression of GLP1R on CHO-K1/GLP1R/Gα15 stable cell line. The fluorescence signal of the target protein on cell product (red) was compared to negative control (green) and detected with GLP1R Antibody (Cat. No. A01826, GenScript) followed by FITC conjugated Goat anti-Mouse IgG Antibody (H+L) (Cat. No. ab6785, Abcam).

Figure 3. Dose dependent stimulation of intracellular cAMP mobilization upon treatment with calcitonin in CHO-K1/GLP1R/Gα15 cells. d2 acceptor fluorophore-labeled cAMP (Cat. No. 62AM4PEC; Revvity) and intracellular cAMP in CHO-K1/GLP1R/Gα15 cells competitively bind with Europium Cryptate-labeled anti-cAMP monoclonal antibody. The FRET signal decreases as the intracellular cAMP concentration rises and was measured by plate reader (Varioskan, Thermo Fisher). The EC₅₀ of GLP-1 (7-37) was 1.84 nM.